using System;
namespace Velocity4Net.App.Events
{
/** 
 * Strategy object used to execute event handler method.  Will be called
 * while looping through all the chained event handler implementations.
 * Each EventHandler method call should have a parallel executor object
 * defined.  
 *
 * @author <a href="mailto:wglass@forio.com">Will Glass-Husain</a>
 * @version $Id: EventHandlerMethodExecutor.java 685685 2008-08-13 21:43:27Z nbubna $
 * @since 1.5
 */
public interface EventHandlerMethodExecutor
{
    /**
     * Execute the event handler method.  If Object is not null, do not 
     * iterate further through the handler chain.
     * If appropriate, the returned Object will be the return value.
     *  
     * @param handler call the appropriate method on this handler
     * @exception Exception generic exception potentially thrown by event handlers
     */
     void execute(EventHandler handler);

    /**
     * Called after execute() to see if iterating should stop. Should
     * always return false before method execute() is run.
     * 
     * @return true if no more event handlers for this method should be called.
     */
     bool isDone();

    /**
     * Get return value at end of all the iterations
     * 
     * @return null if no return value is required
     */
     Object getReturnValue();
}
}